Do you need to know how to surf with the waves?


Have you ever tried surfing and given up? Don’t feel guilty. Surfing a board is like a crash course in classical mechanics – it is only at the end of it that you learn to find the perfect balance between physical forces that change rapidly and act in different directions.

Surfing and Archimedes. Even with the calm, confined sea lying face down on a table, gravity and Archimedes’ strength compete. The first pushes the rider and his board down, and the second responds with an upward force equal to the weight of the moving water.

As the slab is made of a material less dense than the water below, buoyancy wins. Then there is the wave, of course, the intrinsic physical phenomenon. Energy transfer from a water molecule to a water molecule that can cross the sea for miles; Near the shore, the bottom of the wave creates friction with the seabed, while the top rises and produces a ridge.

Surface tension also plays a role, it is the force that causes the water molecules to attract each other, creating a kind of film: it helps to maintain the shape of the wave and helps to s ‘move away from the board. As any surfer knows, when a wave approaches, it’s not enough to just stand aside and wait for it. You should expect to swim for speed before you get stuck.

Newton is also involved. Ideally, the surfer should be at the same speed as the wave, i.e. with enough kinetic energy to make the wave move a bit, to keep the board moving and to overcome the friction of the water. , which in turn can stop it. A few meters away. A perfect explanation of Newton’s First Law, which states that a body in uniform rectilinear motion tends to keep moving.


Extract from the article by Nicola Nosingo published in Focus 346 – August 2021.


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